(1) Field of the Invention
The present invention relates to a proximity warning system for helicopters with the features of the preamble of claim 1.
(2) Description of Related Art
There is a need for a helicopter obstacle detection and rotor strike warning system.
The document DE4328573 A1 discloses an all-weather sight system which combines information from a radar sensor based on ROSAR with navigation and flight control information to produce a synthetic sight for the pilot. In this case, the radar uses the rotary movements of rotating arms—in this case in the form of a capstan (spider) mounted above the rotor axis—which is protected against aerodynamic forces by an aerodynamically formed body (radome). The radar transmitter as well as the radar receiver are positioned on the rotor head.
The document WO2011136707 A1 discloses a helicopter obstacle detection and information system arranged to transmit laser light and receive reflected laser light from obstacles for detecting and informing the pilot of a helicopter of obstacles in proximity of the helicopter. The system comprises an obstacle detection sensor unit, being arranged to be mounted on a rotor head of a helicopter such that said obstacle detection sensor unit is arranged to rotate with said rotor head. The system further comprises an information unit. The transmitted laser light is arranged to cover a sector volume around a rotor head axis, having a coverage defined as a radial extension (R1, R2) in a sector plane around said rotor head axis and an angular extension perpendicular to said sector plane. Communication means are arranged for communication between said sensor unit and said information unit.
The document DE102006053354 A1 discloses a system with radar sensors (RS0, RSm, RS (m+1), RSn) transmitting signals to a detection and evaluation unit, where the signals represent distance information. The unit displays the signals on a cockpit-display after processing and comparing the information with a preset warning threshold value. The sensors operate with short-range and long-range wavelengths for scanning a sphere within, rear and lateral of the helicopter and a sphere in front of a helicopter, respectively. The information regarding obstacles displayed on the cockpit display is restricted to distances in a number of sectors. A footprint is received by the signals for identification and differentiation between aircrafts.
The document DE 10 015 164 A1 discloses a method of operating a heliradar with a laser radar in a helicopter, using a sensor. The sensor data is merged with a data registered in an on-board-intrinsic database and accordingly the flight path and the landing location are displayed in a virtual cockpit display. The method involves the operation of a heliradar with a laser radar in a helicopter, using a sensor. The sensor data is merged with a data registered in an on-board-intrinsic database and accordingly the flight path and the landing location are displayed in a virtual cockpit display
The document WO2007/024635 A2 discloses an obstacle avoidance system including an input control device, a sensor suite, and a communication feedback loop. The input control device is preferably operable to create a first force, while the sensor suite is configured to detect nearby obstacles, and the communication feedback loop is in communication with the input control device and the senor suite so that said communication feedback loop is operable to generate a command signal in response to detection of a nearby obstacle. Preferably, the obstacle avoidance system is used in combination with an apparatus, such as a rotary wing aircraft.
The obstacle avoidance systems of the state of the art provide a synthetic radiating aperture by rotating an antenna along a circular path with a radius r, said synthetic radiating aperture being used—after complex measurements of the precise path and elaborate calculations—for assessment of the radar resolution in azimuth.